The Performance of small samples in quantifying structure central Zagros forests utilizing the indexes based on the nearest neighbors

Abstract Todaychr('39')s forest structure issue has converted to one of the main ecological debates in forest science. Determination of forest structure characteristics is necessary to investigate stands changing process, for silviculture interventions and revival operations planning. In order to investigate structure of the part of Ghale-Gol forests in Khorramabad, a set of indices such as Clark and Evans and uniform angle indices, mingling, domination and differentiation were used based on the nearest neighbors. For this purpose, 80 circular sample sizes with 12 (acer) areas were collected in the field using a random sampling pattern and these plots were analyzed by Crancod (Ver.1.4) software. Based on the results, the average of Clark and Evans and uniform angle indices were calculated 0.936 and 0.449, respectively. These results show that the samples have a random distribution with the tendency to be uniform. Also, the result obtained from the average of mingling index was 0.181 that indicated low species mixture. In the study of the diversity of tree dimensions, the average of domination and differentiation indices of the crown area were 0.449 and 0.519, respectively, which shows that neighboring trees had a clear difference with each other in terms of the crown area. According to the results, in the Zagros forests which often consist of wide and pure oak stands, using small sample size caused to reduced time and cost of field survey, recordation of the sample size position, trees and shrubs accurately as well as the possibility of surveying and monitoring different forest features are suitable for quantification of forests structure.